1. Field
Example embodiments relate to display devices. Other example embodiments relate to display devices including a driving unit having an oxide semiconductor thin film transistor.
2. Description of the Related Art
Conventional display devices (e.g., liquid crystal displays (LCD) or organic light emitting devices (OLED)) may have a driving unit including at least one thin film transistor (TFT) and at least one storage capacitor. The storage capacitor retains a constant voltage by accumulating charges for a desired period of time. The storage capacitor may have a structure in which an insulator is inserted between two electrodes. For example, in an LCD, the storage capacitor may have a structure in which a gate insulating layer and a passivation layer are between a storage electrode formed of a gate metal and a pixel electrode formed of a transparent conductor. The storage capacitor may have a structure in which a gate insulating layer is between a storage electrode formed of a gate metal, and a counter electrode formed of a source-drain metal. In order to form the storage electrode, a metal having a substantially low resistance may be used to prevent (or reduce) degradation of image quality due to resistive-capacitive (RC) delay. However, if the storage electrode is formed using the metal having substantially low resistance, light incident from a backlight unit may not pass through the storage electrode, decreasing the panel light transmittivity. Because a sufficient charge capacity is needed to retain a constant pixel voltage during a frame, reduction of the surface area of the storage electrode, in order to prevent the panel light transmittivity from decreasing, may be limited For similar reasons, the panel light transmittivity in an OLED may decrease due to a plurality of storage capacitors.